Submarine signaling cable



. 8, 1931. J. J. GILBERT SUBMARINE SIGNALING CABLE Filed March 23, 1929'By WM ATTORNEY Patented Dec. 8, 1931 JOHN J. ernaar, or ,pnouenasfromnew LABoaArronInsmoonronarnnorNEWYoan, N. y., Agcnronnmion Vor 4New YORKsuBMarNn sienaninecainn .,nppncationfnaMarchas; "1929. seriali-Naerasing".

Thelp-resentinventionlrelates to submarine signaling, and particularly*to the -eiiicient transmissioneoflvoicefrequency currents overlong'loaded submarine cables;4

An object V,of the inventionfiis to decrease the attenuation of Vvoicefrequency currents transmitted over a long loaded ysi'ibmarine signalingcable. v Y* i Y Another object off'tlleinveht'ion is to'reduce theYeffects `'of extraneous disturbances upon telephone currentstransmitted over long loaded submarine cables. v

Another object of the invention is to reduce the effects of extraneousinterference upon the twin core termination of a single core submarinesignaling` cable.

A further object of the invention is to -rev duce reflection andmodulation losses in the head end sections of a submarine signalingcable and consequently to increase the eliiciency of transmission of thecable as a whole.

F or long distance telephone or high frequency transmission a twin corecable structure possesses important advantages in the way of-freedomfrom interference. The terminal sections of such a cable are the most'critical portions both from the standpoint of losses due to theunsually great current lat the transmitting end but also due to the factthat interference is likely to be most troublesome near the terminals.For practical reasons, a long deep sea signaling cable is usuallymanufactured in a number of sections of about one mile length whichlaying operation. Owing to inherent manu-y facturing conditions theelectrical properties of the individual sections will not be identicalin all sections. There are .particularly three electricalcharacteristics of primaryimportance, herein referred to as theparameters, which will be found to differ, namely, first, the initialinductance (i. e. the inductance at Zero current density) second, thecapacity; and third, the variation of hysteresis resistance withcurrent. s

The present invention ,makes use ofthese facts and applies them in thefollowing manner: During manufacture, the parameters of the cores aremeasured and from lthe results of these measurements the cores areselected are joined during the into `groups Lso Lthat ithe y'cores inv:any `group have `as Vnearly as 'possible identical initial inductance)Of the members of any Vgroup Yonnfassrenon no yanni. `,griirfiiirrour.1.1

there arethen selected pairshavingasnearly o as possible the samecapacity. The -conductors ar-e thenf twistedA or-laid together`spir'ally 'intopalirs andthe-'pairs arranged 'in order-fof decreasinghysteresis resistance. During? the Y laying ofthe ,cabler thepairhavingthe lowest i hysteresis'resistanee is placedvnear the cableterminal and l'those pairs having successively higher hysteresisresistance are placed in successive positions more )remote 'from theA1terminal. I'For a two-way cable the Y other jterminal will :be treatedinithe same fashion. Ina cable in accordancewiththe present inventionthe separately Ymeasured l'impedanc'es of fthe 'twinned cores *measuredfrom anyf'two points on-fthe cable and looking t the same direction will'f be as A`nearly equal'` as This has the advantage-@that eX possible.traneous interfering electric and magnetic fields, 'such asthoseemanating from :nei-ghboring electriccables,fromthe effects oftheearths-:magneticeld and lfrom static disturbances Awillloe'balanced outAwith respect 'to A'the twin core cable. Y Also in the terminal sectionsof'the cablewheretheflargest currents are encountered, the increase of4attenuation due-:to hysteresis willbe minimized. v

'The ,eect of extraneousfinterferenceisreduced by matching-the cores yasregards the inductance andvcapacityg and at the same time sthe increasedattenuation due to 1 hysteresisalosszisniinimized.' l The hysteresisresist# ance, upon which'the increasedlattenuation depends, is,

one,ccnductor to-another. An limportant featu-reofthe invention,therefore,is to use inthe ihead end-sections of the cable, `wlfiere thelcurrent' islarge,vcores .whichhave a-smail-l value forithisconstant lofproportionality; lrnthe.- .case :ofra ztwinvcore :termination .offasingle core cable the niethod of selecting in aV shortllengthiofconductor, Vproportional tothe current inthe; conductor. The constant of:proportionality var-ies from cores may :abe somewhat :different from:that

employed in the manufacture fof' a r twin ecore" cable.` Theicalolecoresjimayiiirstloegrouped' as vregards @hysteresis resistance, vthosehaving low hysteresis resistance being selected for the terminalsections. These cores may then be paired so as to obtain the desiredbalance to.: Suitable heat treating of inductance and capacity. It ishowever, possible to use this same method of selection also in themanufacture of a twin core cable. In, the "accompanying drawings whichshow one embodiment of the invention `:A e,

The central copper conductors 10 are surrounded by a numberof segments11,say six, shaped" /towlit the:v central conductors "110. Upon thesegments 11 is applied a helix of loading material 12. Suitable loadingmaterials and suitable methods of applying loadmg materials are knownand need not be dis'- cussed herein. v 'I heconductor, is heat treatedafter the' loading material applied theremethods such as are .well knownmay be employed. The loading material is surrounded by a pressureequalizing fluid, such as liquid bitumen or melted rubber;-

Surrounding Vthe loading Y material is a sheathof insulating material 13selecting k,from a group thus A tute.

`scribed constitutes a unit hereinafter re` such as gutta percha orguttapercha substi- The entlre structure` thus far de# ferred to asaY-core. Two such cores are twinned together in a twinning-machine andgiven a spiral lay or pitch as indicated in Fig. 2. The pitch ispreferably of the order of several feet. In order to give this twinnedcore the cylindrical shape requiredfor armoring, the interiorly cuspedcrescent shaped spaces on both sides thereof are iilled by a suitablefiller 14, suchas jute, which is moldled around the twinned cores toproduce a spherical cross-section. Teredo tape 15, jute16,andarmorrwires 17 are provided to surround the cores in asuitablemanner. Y

l The invention has .been described specifically as applied to acontinuously loaded subrine cable which comprisesselecting from a numberVoi" core lengths agroup having, Vas nearly aspcssible, equalityfofinductances, rformed @pairs having, as nearly as possible, equality ofcae pacity, to'form. a twin core section, and arranging the twin coresections ythus formed in order of increasing'hysteresis(resistancelosses as one proceeds-from the terminal toward the center of the cable.e.

vand lplacing those each to the other, las to one parameter and the twincores are arranged progressively in the cable in accordance with adifferent parameter.

3. A submarine cable of the twin core type in which the twin corelengths of a section are matched each to the other as to theirinductance characteristics and the twin core lengths are arrangedprogressively in the cable in accordancewith increasing hysteresisresistance as one proceeds fromv a terminal toward the center of thecable;

"4.' Inl constructing a submarine signaling cable of great overallattenuation from sections of loaded cores the impedance of which varies,the method of reducing irregularities inthe completed cable, whichmethod comprises arranging the sections in pairs balanced with respectto their impedance values, pairs havingl the highest hysteresisresistance toward the mid-portion of the cable v v A In witness whereof,I hereunto subscribe my name this 15th day of March, 1929.

- JOHN A J. GILBERT.

i "2. VA submarinecable of twin'coreitype l which thetwin corelengthsare matched,

